The field of the present invention relates to archery equipment. In particular, a nock for an arrow or bolt is described herein that permits multiple relative orientations of a nocked arrow or bolt and a bowstring.
A conventional arrow or bolt includes a single transverse notch or groove 86 (the nock; a conventional nock member 85 is shown in FIG. 1) on the rearward end of its shaft for receiving the bowstring of a bow or crossbow. The term “bolt” typically refers to a relatively shorter, heavier arrow used in a crossbow; “arrow” and “bolt” shall be considered interchangeable for purposes of the present disclosure or appended claims. The single groove 86 of a conventional nock member 85 allows the arrow or bolt to be fitted to the bowstring in one of only two relative orientations; typically, only one of those two relative orientations is the correct one (discussed further below).
The most common arrangement of the fletching of an arrow or bolt 80 includes three longitudinal vanes 88a, 88b, and 88c (collectively, vanes or fletching 88x; FIGS. 2-4). The vanes 88x are each attached to a rearward portion of a circumferential surface of the shaft 82 along corresponding substantially longitudinal lines of attachment and extend transversely from the shaft 82. The corresponding lines of attachment are separated from one another by angles of about 120° about the longitudinal axis of the shaft 82. The single groove 86 of the conventional nock is arranged to be substantially perpendicular to a diameter of the shaft that coincides with the line of attachment of one of the three vanes 88x (as in FIG. 2). That vane is referred to as the “cock” vane 88a; the other two vanes are referred to as the “hen” vanes 88b and 88c. 
When, in preparation for shooting the arrow 80, a conventional, single-nock arrow 80 is fitted onto the bowstring 99 (i.e., “nocked”) of a vertical archery bow (i.e., a bow that is not a crossbow), the correct relative orientation of the arrow and bowstring is typically chosen so that the cock vane 88a points away from the bow riser 92 and the hen vanes 88b and 88c are on the side of the arrow closer to the bow riser 92 (as in FIG. 3). That arrangement reduces interference (relative to the other relative orientation wherein the cock vane 88a points toward the bow riser 92) between the fletching 88 and the bow riser 92 as the arrow 80 is launched past the bow riser 92 upon releasing the drawn bowstring 99.
When a conventional, single-nock bolt 80 is loaded into a crossbow, it typically rests on a longitudinal rail 94 (as in FIG. 4). The rail 94 has a midline slot; the bolt 80 typically is placed on the rail 94 with the cock vane 88a extending downward into the slot, which results in the nock groove 86 being oriented substantially horizontally, substantially aligned with and parallel to the bowstring 99 of the crossbow. If instead one of the hen vanes 88b or 88c is placed in the midline slot of the rail 94, however, the nock groove 86 and the bowstring 99 are not properly aligned, instead forming about a 60° angle with respect to one another (not shown). That misalignment of the nock groove 86 and bowstring 99 can lead to a range of undesirable consequences, including one or more of the following. The lack of proper engagement of the bowstring 99 with the nock groove 86 can lead to inaccurate movement of the bolt 80 along the rail 94 and an inconsistent or unpredictable flight path of the bolt 80. The bowstring 99 can lose contact with the nock altogether, leading to a misfire of the crossbow and potentially damaging the bolt 80 or crossbow or injuring the archer. In certain instances, e.g., if the bolt 80 has a so-called “half-moon” nock with somewhat sharp edges (as in FIG. 1), the misaligned nock can sever the bowstring 99 when the crossbow is fired, destroying the bowstring 99 and potentially damaging the crossbow severely or injuring the archer.